Arthropods

The
phylum
of
arthropods
has
the
largest
number
of
species
known
on
earth
today.
It is
the
phylum
of the
ubiquitous
insects
and
even
trilobites.
Arthropods
belong
to the superphylum
Ecdysozoa.
They
are
protostomians.
They
are
bilaterally
symmetrical
animals
with
segmentation
called
somites.
They
have
paired
limbs,
chitinous
cuticle
as an
exoskeletal
covering
and a
reduced
coelom
which
extends
into a
haemocoele.
They
exhibit
tagmatosis
which
is the
formation
of
tagmata
(divisions)
of the
limbs.
There
is
also
conspicuous
cephalization.